Scores of people were injured as violence erupted in Macedonia's parliament after nationalist protesters stormed the building in anger over a vote for a new speaker, the interior ministry said on Friday.

The chaos in Skopje broke out on Thursday evening, with dozens of demonstrators — including a group of masked men — breaking a police cordon and entering parliament waving Macedonian flags, shouting and singing the national anthem.

Footage from the scene showed chairs being thrown as fistfights broke out in the parliamentary press room, while Zoran Zaev, leader of the opposition Social Democrats (SDSM), had blood running down his face and shirt.

One female SDSM deputy is seen yanked by the hair while other women climb down from a balcony in a bid to escape.

An interior ministry statement on Friday said 102 people had been treated at city hospitals, including MPs and police officers.

Interior Minister Agim Nuhiu earlier told media that 10 MPs and an unspecified number of journalists were among those hurt in the violence, which was condemned by the United States and European Union.

The ministry said the situation was "normalised" on Friday morning but that there were "additional measures and activities to protect the security of citizens".

The incident follows two years of political crisis in the Balkan country, where nationalist demonstrators — who support the conservative VMRO-DPMNE party — have been holding nightly rallies since an inconclusive December election.

They oppose a proposed coalition between the SDSM and ethnic Albanians, which they perceive as a threat to national unity.

VMRO-DPMNE leader Nikola Gruevski was Macedonia's premier for a decade until last year.

Thursday's turmoil broke out after the SDSM and Albanian parties voted in a new parliamentary speaker, ethnic Albanian Talat Xhaferi.

Their opponents say the vote was unfair, taking place after the former speaker had closed the day's session, but the EU said it took "positive note" of Xhaferi's election.

Most of the injured deputies were from the SDSM party, but ethnic Albanian MP Ziadin Sela appeared to be one of the most badly wounded.

Police eventually took control of the parliament, using stun grenades to clear out the protesters.

President Gjorge Ivanov made a brief televised speech late Thursday, appealing for calm and inviting party leaders to his office on Friday to discuss the situation.